It is the object of this communication to review the history of our knowledge of the giant cell tumor of bone, emphasizing its invariable failure to produce metastases; and to record a case in which this rule was broken in the case of a tumor which completely altered its original structural character and proved fatal, with pulmonary metastases, apparently as the result of repeated insults from attempted surgical removal, irradiation and infection. Between 1840 and 1860, medullary tumors of bone received much attention from European surgeons and pathologists, and this interest culminated in 1860 in the appearance of an elaborate monograph by Nelaton,1 in which nearly all that we now know about benign medullary tumors was clearly presented. Before that time, medullary tumors were variously described and designated and vaguely interpreted. Ambrose Pare2 recognized benign tumors of the maxillae which were curable by repeated excision. Under the term